This project is concerned with the development of statistical and mathematical methodology useful in the assessment of risks associated with exposures to potentially hazardous environmental and occupational agents. A major focal point is the generation of improved statistical techniques for estimating adverse human health effects from laboratory animal data, with particular emphasis being placed on dose-response modeling, low-dose extrapolation and extrapolation of toxicologic responses across species. Consideration is also given to the modeling of epidemiologic data in the risk assessment process. Current research efforts are concerned with the continuing evaluation of procedures for estimating carcinogenic potency, with the investigation of factors that appear to affect the correlation between background or natural radiation levels and various types of chronic disease mortality, and with the quantification of human teratogenic risk.